#define ISALNUM(c) isalnum (CHAR(c))
#define ISALPHA(c) isalpha (CHAR(c))
#define ISDIGIT(c) isdigit (CHAR(c))
-#define ISUPPER(c) isupper (CHAR(c))
#define ISLOWER(c) islower (CHAR(c))
#define lowcase(c) tolower (CHAR(c))
#ifdef DOS_NT
/* Canonicalize drive letter case. */
+# define ISUPPER(c) isupper (CHAR(c))
if (fn[0] != '\0' && fn[1] == ':' && ISUPPER (fn[0]))
fn[0] = lowcase (fn[0]);